Tuning tab (RAFM mode)

Parameters of the cantilever resonance tuning can be configured here. In the Tuning mode Deflection-Frequency and Phase-Frequency dependences are obtaining. F0 and F1 parameters define initial frequency range. If N scans field is in "continuous" state, than manual tuning is preformed. In other case resonance is tuned in automatic mode. In automatic mode program acquire 'N scans' number of resonance curves and average them. Then it chooses the highest resonance peak and tuned the modulation amplitude in a way that resonance amplitude signal is equal to value in the Defl. field (see 2.2.2). The frequency range is decreasing until amplitude values at the ends of current frequency range exceed half of the resonance amplitude.

In the manual tuning mode amplitude-frequency dependence is obtained continuously and user should choose resonance peak needed by placing it between two cross-like pointers (see pic. 2.9) and press Zoom In button. Then the program sets new frequency range and changes modulation amplitude in a way that maximum amplitude signal in this range being equal to value in the Defl. field. Note that zero-level of resonance amplitude is set by the program using first amplitude-frequency dependence scan. So if the tuning has been started with very narrow frequency range it can lead to errors in zero amplitude estimation. Due to the wrong zero level wrong modulation amplitudes will be calculated during tuning.

Figure 2.9: Resonance tuning.